A data storage device comprises a nonvolatile semiconductor storage array containing data, a controller in communication with the nonvolatile semiconductor storage array, and a buffer containing RAID units, the RAID units being in communication with the nonvolatile semiconductor storage array via the controller. The controller is configured to receive write requests from a host device, and accumulate first data relating to the write requests in the RAID units. The controller is also configured to, concurrently, transfer the first data contained in the RAID units to the nonvolatile semiconductor storage array, calculate parity values of the first data contained in the RAID units, each parity value relating to each write request, and accumulate the parity values in a context identifier buffer. The controller is further configured to associate context identifiers with the parity values, and store the parity values and the context identifiers in the nonvolatile semiconductor storage array.